Melt dispensers

ABSTRACT

A device for use in a hand held hot melt gun to prevent drool of melted composition from the outlet thereof when the gun is not in use is described and claimed. In one embodiment of the invention the device comprises a melt body 10 having a melt chamber 12, resilient means provided by a coil spring 26 and means 36 for heating the melt body. When in use a rod of composition urged by a feeding force in a direction towards the melt body 10 is melted in the melt chamber 12 and is dispensed in molten condition from the outlet 20. When the feeding force is released after use the spring exerts sufficient force in a reverse direction to the direction of the feeding force to move the rod outwardly of the melt body, which relieves the pressure within the melt body and thereby substantially prevents further composition from drooling from the outlet.

TECHNICAL FIELD

This invention relates to melt dispensers.

Various proposals have been made to provide apparatus for melting anddispensing thermoplastic material supplied in the form of a rod. Suchapparatus is usually provided with a melt body having a melt chamber inwhich thermoplastic material is melted, an inlet for the rod and anoutlet comprising an orifice for dispensing melted material, and meansfor heating the melt body so that composition fed as a rod into the meltchamber may be dispensed in molten condition from the orifice. Suchapparatus finds use in various fields of application, an importantexample being hand held glue guns having provision for feeding a rod ofadhesive to the melt body for example by direct thumb pressure or bytrigger operated means.

BACKGROUND ART

A persistent problem associated with hot melt dispensers which rely onfeeding of the rod to cause outflow of molten composition from theorifice is the drooling of cement from the orifice which tends to occurwhen feeding of the rod ceases and the melt body remains hot. Thisdrooling is wasteful, inconvenient and messy. While the employment ofcheck valves has assisted in reducing drool, it remains highly desirableto provide an inexpensive means for further reducing or eliminatingdrool. Proposals have been made to physically pull the rod of adhesiveout of the melt body to a limited extent, but such proposals requirecomplications in the mechanism of the apparatus with consequent increasein its weight and/or cost and furthermore such proposals are ineffectivewhen there is a discontinuity in the rod between the pulling mechanismand the melt chamber, as may occur for example when the rod is made upof short sticks of adhesive held together merely by pressure exerted tofeed the rod, as is the case particularly for example in the case ofglue guns normally used by "do it yourself" enthusiasts.

It is one of the various objects of the present invention to provide animproved device for melting and dispensing thermoplastic materialsupplied in the form of a rod.

DISCLOSURE OF INVENTION

The invention provides as one of its aspects a device for melting anddispensing thermoplastic material supplied in the form of a rodcomprising a melt body having an inlet end and an outlet end and a meltchamber within the melt body, the inlet end being adapted to receive asolid rod of composition as it is fed to the melt chamber, and theoutlet end having an orifice, means for heating the melt body so thatcomposition fed into the melt chamber via the inlet end in the form of arod may be dispensed in molten condition from the orifice in response toapplication of a feeding force on the rod to urge it in a directiontowards the melt body, and resilient means located within the melt bodyarranged to exert sufficient force in a reverse direction to move therod outwardly of the melt body when the feeding force is not applied.

In a device according to the invention, the resilient means ispreferably provided by a coil spring trapped in the melt body andarranged to act directly or indirectly upon a solid portion of a rod fedinto the melt chamber. As a first embodiment of the inventionhereinafter described, the coil spring is arranged to bear directly onthe advancing solid end of the rod. As a second embodiment of theinvention, the coil spring is arranged to bear upon a melt chamberelement which is slidable in the melt body, whereby to move the meltchamber element and the advancing solid end of the rod entering the meltchamber outwardly of the melt body when the feeding force is notapplied.

Preferably the spring does not reduce the melting capacity of the meltbody and thus, the spring preferably is in heat conductive contact withthe melt body, so that it may be heated by transfer of heat from themelt body, and so contribute to melting of the thermoplastic material.

In a simple form of the invention, for example the first embodimenthereinafter described, preferably a coil of the spring furthermost fromthe inlet end is located in a recess in the melt body, and is in goodheat conductive contact with the melt body. Preferably an end portion ofthe spring near to the inlet end is formed to provide a portionextending across the end of the spring. Preferably the spring is of asize and strength that its outer surfaces are in close proximity towalls of the chamber, that it is not distorted to interferesignificantly with passage of melted thermoplastic material through themelt chamber during feeding a rod, and that it may move a rod outwardlyof the melt body when feeding pressure is removed, and yet is not sostrong as to eject the rod entirely from the melt body.

In a more sophisticated form of the invention, for example the secondembodiment hereinafter described, the spring is preferably arranged sothat it is of a size and strength that its outer surfaces are in closeproximity to walls of the melt body, that it is not distorted tointerfere significantly with passage of melted thermoplastic materialthrough the melt chamber during feeding a rod and that it may move themelt chamber element and rod outwardly of the melt body when feedingpressure is removed.

In both forms of the invention desirably the spring when relaxed i.e.when the feeding force is not applied, is of a size sufficient torelieve the pressure of composition within the melt body which urgesfurther composition out through the orifice, thereby substantiallypreventing the drool of melted composition from the orifice, but doesnot move the rod so far outwardly of the melt body that air will bedrawn into the melt body through the orifice.

Preferably the coil spring used in a device according to the inventionis of a wire material that is not deleteriously affected by theenvironment within the melt body which may be maintained at temperaturesof the order of 230° C. or even higher, and which under extremeconditions may also contain decomposition products of the rod. Thecharacteristics desired of the spring may differ according to thecomposition of the rod, for example, where a rod having a smooth surfaceis employed, the frictional force between the rod and lip means(hereinafter described) will be less than for a rod having a roughsurface, hence the spring will have to exert a lesser force to urge asmooth rod outwardly of the melt body as for a rod having a roughsurface. We have found coil springs formed from 2 mm diameter wire of astainless steel alloy according to German standard 1.4310, UK B.S. 304 S62 or USA A1A1 301 comprising about eight turns and having an overallspring length of about 5 cm, which have been subjected to an additionalheat treatment of 300° C., to be most suitable for use in a cylindricalportion of a melt body which cylindrical portion has a length of 5.6 cmand a diameter of 1.9 cm.

A device according to the invention preferably comprises an inlet sleeveof resilient material through which a rod may be introduced to the meltchamber. Preferably the resilient sleeve is provided with lip meanswhich clasp a rod fed to the melt chamber to minimise back flow ofmelted composition along the rod. Conveniently in a simpler form ofdevice according to the invention, the lip means may be of a size toensure that the resilient rod returning means does not accidentallybecome removed from the melt chamber.

In another of its aspects the invention provides a device for meltingand dispensing thermoplastic material supplied in the form of a rodcomprising a melt body having an inlet end and an outlet end, a passageextending between the inlet end and the outlet end and means formounting a nozzle assembly at the outlet end wherein the passage isadapted to receive a melt chamber element in such a way that the meltchamber element may be caused to slide within the melt body and may beheated from the melt body to an extent sufficient to melt thermoplasticmaterial fed to the melt chamber. In such a device the nozzle assemblymay be releasably mounted at the outlet end so that the melt chamberelement may be removed from the melt body when the nozzle assembly isreleased from the melt body.

In a device according to the invention, the melt chamber may be of anydesired form or configuration so that it may be adapted to receive a rodof any shape for example a rod having a circular, rectangular ortriangular section. As the first embodiment of the invention hereinafterdescribed to illustrate the invention by way of example the melt chamberis provided by a passage in the melt body shaped to define a conicalsurface tapering from a cylindrical surface shaped to accept a rod ofcomposition fed thereto. As the second embodiment of the inventionhereinafter described to illustrate the invention by way of example themelt body has a passage extending between its inlet end and outlet endwhich is adapted to receive a melt chamber element in such a way thatthe melt chamber element may be caused to slide within the melt body andmay be heated from the melt body to an extent sufficient to meltthermoplastic material fed to the melt chamber. The melt chamber isprovided in the melt chamber element, and has an inlet through which arod of composition may be inserted into the chamber and an outlet fromwhich melted composition may be dispensed and fin elements disposedlengthwise within the chamber progressively increasing in sizeconsidered in a direction extending from the inlet to the outlet, soshaped and located that edge surfaces thereof disposed towards aninterior of the chamber define surface portions of an opening ofprogressively reducing cross section, the peak of which opening islocated adjacent the outlet but on the inlet side thereof and so thatend portions of the fin elements at the outlet are spaced to define aseries of exit slots spaced about an axis of the opening to provide theoutlet. At least one housing is provided in the melt body for receivingelectrically operated heating means for heating the melt body. A meltchamber of such configuration is described and claimed in UK patentapplication No. 8419303.

In a device according to the invention the orifice is preferably shapedto provide a dispensing nozzle or to communicate with a nozzle assemblyadapted to be secured to the melt body. Preferably a ball valve isprovided to assist in controlling flow of composition from the orifice.

In a device according to the invention the means for heating the meltbody may be provided in any convenient form. We prefer to employ one ormore electrical heaters of the PTC type.

A device according to the invention may be used for dispensing variousmaterials including adhesives and sealants supplied in cylindrical stickor rod form, and may be incorporated in apparatus appropriate to theintended purpose. Preferably a device according to the invention isincorporated in a hand held glue gun, which may be arranged so thatthermoplastic rod is fed to the melt body under direct thumb pressurefrom the hand of an operator of the gun, or more preferably is arrangedso that thermoplastic rod is fed to the melt chamber by a mechanismactuated by a trigger of the gun for example as shown in registereddesigns Nos. 1009681 or 1009682 or as described in German patentapplication No. 33 20 041.

By use of a device according to the invention, in which resilient meansfor moving a rod outwardly of the melt body when the feeding force isnot applied is housed entirely within the melt body, unwanted drool isat least substantially eliminated. Also it is possible to provide returncontrol of the rod and therefore of pressure of melt within the meltbody even when only a small amount of rod remains to be fed. This is animportant feature where the rod is provided by a series of short gluesticks fed end to end, as regularly happens in the field of glue gunsand particularly in so called D.I.Y. activities. Furthermore byselection of an appropriate coil spring, the device remainscomparatively inexpensive and uncomplicated. By use of an arrangement inwhich the resilient means is arranged to bear upon the melt chamberelement to urge it towards the inlet end, thus to move the melt chamberelement and rod outwardly of the melt body one may also realize theadditional advantage that the resilient means is conveniently trappedwithin the melt body and is unlikely to be removed when unwantedunmelted rod is pulled from the inlet end of the melt body.

In order that the invention may become more clear, there now follows adetailed description to be read with the accompanying drawings of twoexample devices according to the invention and illustrative thereof. Itis to be understood that the illustrative devices have been selected fordescription to illustrate the invention by way of example and not by wayof limitation thereof.

BRIEF DESCRIPTION OF DRAWINGS

In the drawings:

FIG. 1 is a sectional view of the first illustrative device;

FIG. 2 is a view of a spring shown in FIG. 1;

FIG. 3 is a sectional view taken substantially on the line III--III ofFIG. 1 viewed in the direction of the arrows;

FIG. 4 is a sectional view of the second illustrative device showingparts in positions assumed during feeding of a rod;

FIG. 5 is a sectional view of the second illustrative device showingparts in positions assumed prior to feeding of a rod; and

FIG. 6 is a side view of a hot melt hand held gun incorporating thesecond illustrative device.

MODES FOR CARRYING OUT THE INVENTION

The illustrative devices each provide a device for melting anddispensing thermoplastic material supplied in the form of a rodcomprising a melt body having an inlet end and an outlet end and a meltchamber within the melt body, the inlet end being adapted to receive asolid rod of composition as it is fed to the melt chamber, and theoutlet end having an orifice, means for heating the melt body so thatcomposition fed into the melt chamber via the inlet end in the form of arod may be dispensed in molten condition from the orifice in response toapplication of a feeding force on the rod to urge it in a directiontowards the melt body, and resilient means located within the melt bodyarranged to exert sufficient force in a reverse direction to move therod outwardly of the melt body when the feeding force is not applied.

In the first illustrative device, the melt body 10 comprises a castingof a heat conductive alloy formed with a passage to provide a meltchamber 12, defined by a conical surface 14 tapering from an adjacentcylindrical surface 16. The melt body has an inlet end 18 ofsubstantially cylindrical section at one end of the cylindrical surface16, and an outlet end 20 at a narrowed end of the conical surface 14,having an orifice 22. A spring loaded ball valve 24 is located withinthe melt chamber adjacent the outlet end 20. Resilient means in the formof a coil spring 26 is housed in the melt chamber, with its leading coilheld in a recess in the melt body between the cylindrical and conicalsurfaces in heat conductive manner.

A flexible moulded silicone rubber inlet sleeve 28 is secured on themelt body over the inlet end by spring means (not shown) with acylindrical inner surface of the sleeve providing an extension of thecylindrical surface 16 of the melt chamber. The sleeve is provided withan inlet opening 30 of sufficient size to locate and guide a rod ofcomposition which is to be fed to the melt chamber 12. Lip means 32 isprovided on the interior of the sleeve adjacent the inlet opening 30,which are so shaped and positioned as to exert a gripping action oncomposition fed through the inlet opening in the form of a rod of adiameter not substantially less than the diameter of the cylindricalsurface 16 of the melt chamber.

The melt body is provided with a housing 34 for means for heating themelt body which means comprises an electrically operated heating element36 for example provided by a PTC heater connected to a source ofelectricity via leads 38 and arranged to heat the melt body so as tomelt fusible composition in the melt chamber.

The spring 26 comprises a coil of eight turns of stainless steel wire of2 mm diameter according to German standard No. 1.4310 and subjected incourse of its manufacture to an additional heat treatment at 300° C. Thespring terminates at its right hand end as viewed in FIGS. 1 and 2, in afinal turn bent to provide a straight portion 40 which extends acrossthe diameter of the spring to the opposite side of the coil (see FIG.3). The spring is of a diameter sufficient to enable the spring to becompressed and allowed to expand within the melt chamber axially of thespring adjacent the cylindrical surface 16. The diameter of the firstturn of the spring is also larger than the diameter of a circularopening to the conical surface 14 from the cylindrical surface 16. Thediameter of the remainder of the spring is larger than the openingdescribed by the lip means 32. As shown in FIG. 1, prior to compressionthe spring 26 extends rearwardly in the melt chamber to an extent suchthat an end portion of a solid rod may be introduced through the inletend 18 to the melt chamber. The spring is sufficiently robust thatduring feeding of rod into the melt chamber the spring is notsignificantly distorted radially of the spring, and sufficiently strongto gently urge a rod rearwardly of the melt chamber when compressiveforces on the spring are released to move the rod outwardly of the meltbody.

The illustrative device is intended to be incorporated in apparatus formelting and dispensing thermoplastic material, for example a hand heldglue gun, having provision for feeding a rod of adhesive composition tothe apparatus for example by direct thumb pressure or by triggeroperated means. When a rod of adhesive is to be fed into the device;with the heater operating, an end portion of the rod is introduced tothe inlet opening 30 and through the lip means 32 causing the sleeve tobe distended to accommodate the rod. Further pressure on the rod toexert a feed force on the rod urges it to move through the lip means,towards the orifice, and into the cylindrical portion of the meltchamber. A leading end portion of the rod engages the straight portion40 of the spring and the end coil of the spring, and the spring iscompressed. As a result of transfer of heat from the melt body andspring to the leading end portion of the rod, the rod is melted andsubsequent portions of the rod are fed into the melt chamber, with asolid leading portion of unmelted rod in engagement with the spring.Continued exertion of feeding pressure on the rod maintains compressiveforce on the spring and exerts pressure on the melted material in themelt chamber so to cause flow of melted material from the orifice 22 viathe ball valve 24. When the feeding pressure is removed from the rod,pressure on the melt is relieved and flow of melted material from theorifice ceases. Also, the spring exerts sufficient force on the rod tourge the rod outwardly of the melt chamber, and to move the rod a shortdistance outwardly through the lip means. In this way, pressure built upin the melt chamber is further relieved.

In the second illustrative device, the melt body 110 comprises a castingof a heat conductive alloy formed with a passage 112 defined by acylindrical surface. The melt body has an inlet end 118 of substantiallycylindrical section at one end of the cylindrical passage 112, and acircular outlet end 120 at the other end of the passage 112. The passage112 extending between the inlet end and outlet end of the melt body isadapted to receive a melt chamber element 116 in such a way that themelt chamber element may be caused to slide within the melt body and maybe heated from the melt body to an extent sufficient to meltthermoplastic material fed to the melt chamber. The melt chamber isprovided in the melt chamber element, and has an inlet 117 through whicha rod of composition may be fed into the melt chamber and an outlet 119from which melted composition may pass to the outlet end 120 of the meltbody. A nozzle assembly 122 including a spring loaded ball valve isthreadably secured at the outlet end 120 of the melt body. Resilientmeans in the form of a coil spring 126 is housed in the melt body, withits leading coil held in contact with an annular surface of the nozzleassembly and its trailing coil in contact with an end surface of themelt chamber element.

The inlet end 118 of the melt body and the inlet 117 of the melt chamberelement are formed to accept rods of thermoplastic material of circularsection. The passage 112 is of larger diameter than the inlet end 118 toan extent sufficient to slidably receive the melt chamber element sothat contiguous surfaces of the melt chamber element and melt bodysurfaces are in heat conductive contact and so that the inlet end 118and inlet 117 are in register. A shoulder 121 is thus provided betweenthe passage and inlet end which serves to limit rearward movement of themelt chamber element in the melt body.

Fin elements 123 are disposed lengthwise within the chamber element 116,the fin elements 123 protrude from a wall surface of the chamber intothe melt chamber and extend parallel to the axis of the melt chamber andincrease in size towards the outlet. The fin elements comprise major finelements 127 and sub elements, each of which fin elements has a platelike structure having a substantially triangular configuration. Themajor elements 127 are arranged as a tripod within the melt chamberwhich is effective at least towards the outlet 119 of the melt chamberto separate the melt chamber into three sub-chambers and so that inneredge surfaces of the major elements provide surface portions of asubstantially pyramid shaped opening 131 centrally disposed in thechamber and which narrows to a peak located adjacent the outlet 119. Thesub elements are disposed between adjacent major elements.

The spring 126 comprises a coil of 8 turns of stainless steel wire of 2mm diameter according to German standard No. 1.4310 and subjected incourse of its manufacture to an additional heat treatment at 300° C. Thespring is of a diameter sufficient to enable the spring to be compressedand allowed to expand within the melt body axially of the springadjacent the cylindrical passage 112. The diameter of the spring issimilar to that of the melt chamber element. As shown in FIG. 5, priorto compression of the spring 126, the melt chamber element 116 occupiesa rearward position in the melt body in which the melt chamber elementabuts the shoulder 121, and is located so that an end portion of a solidrod may be fed via the inlet end 118 to the inlet 117. During feeding ofrod into the melt chamber the spring 126 is compressed but notsignificantly distorted radially so that the spring and melt chamberassume positions as shown in FIG. 4, i.e. the melt chamber element iscaused by feeding pressure on the rod acting on the fins in the meltchamber to move forwardly in the melt body to an extent permitted by thespring. The spring is sufficiently strong to urge the melt chamberelement 116 rearwardly of the melt body towards the inlet end and thusto move the rod outwardly of the melt body when compressive forces onthe spring are released.

The melt body comprises three housings 139 each having a bore having anaxis parallel to the axis of the passage 112 for receiving electricallyoperated heating means in the form of cylindrical self regulatingheaters 145 comprising PTC resistors distributed about the chamber. Theheaters 145 are of a kind substantially as described in GB PatentSpecification No. 1540482 and are constructed and arranged so that themelt body may be heated to a maximum temperature of about 225° C.Suitable uniform distribution of the heaters is achieved in the meltbody shown together with desirable slim characteristics of the meltbody. Webs 141 and 143 formed between pairs of the housings serve tostrengthen the melt body. Locating bosses 155 (FIG. 6) are formed on themelt body in order to co-operate with sockets formed in the body partsof a glue gun in which the melt body is to be mounted.

The melt body has a threaded bore 147 coaxial with the melt chamber intowhich the nozzle assembly 122 is threaded. This arrangement allows thenozzle assembly 122 to be removed after use for replacement of the meltchamber element or nozzle or cleaning of the melt chamber element and orpassageway 112. This proves advantageous if it is desired to use asecond rod of different composition to that of a first rod previouslyused in the melt body for example having a different softening point. Insuch a case the melt chamber element which contained the first rod maybe removed from the melt body 110 through the outlet end 120 of the meltbody, and another melt chamber element arranged to receive the secondrod inserted into the passageway 112 through the outlet end 120. Thenozzle assembly 122 may then be rethreaded into the threaded bore 147 ofthe melt body.

An outer surface of the inlet end 118 of the melt body is formed toprovide a tube onto which a flexible inlet tube 128 of silicone rubberis secured (FIG. 6). The inlet tube 128 is formed from resilient heatresistant material and has a flange 125 at its forward end and ismaintained in place on the tube by a bell shaped sleeve 129. The inlettube 128 has an inlet passage coaxial with the melt chamber in the meltbody through which a rod of hot melt material, for example an adhesiveor sealant, may be introduced into the inlet end of the melt body andhence to the inlet of the melt chamber. The inlet tube 128 is ofcircular cross section and is formed with an inner lip portion, notshown, so that as well as exerting a gripping action on the rod throughthe inlet opening and guiding the rod of hot melt into the melt chamber,the tube forms a seal with the surface of the rod, militating againstescape of molten hot melt material from the inlet when the rod is fedinto the chamber.

The second illustrative device is intended to be incorporated inapparatus for melting and dispensing thermoplastic material, for examplea hot melt hand held glue gun as shown in FIG. 6.

In the glue gun shown in FIG. 6, the second illustrative device ismounted in body portions of the gun. A locating ring 151 of resilientheat resistant material encircles a forward portion of the melt bodyadjacent the nozzle and is received in co-operating recesses formed inthe gun body portions. The sleeve 129 is formed with a locating ring 137which is received in co-operating grooves formed in the gun bodyportions. The melt body is thus mounted in the body portions at itsoutlet and inlet ends by means of the rings 151 and 137 and at a midportion by means of the bosses 155.

The parts of the gun body are moulded of tough plastics material and aresecured together by fastenings including screws (not shown).

The glue gun is provided with trigger operated feeding means comprisingclamping means comprising a carriage 142, mounted for sliding movementtowards and away from the melt body 110 and a clamp member not shown,pivotally mounted on the carriage 142, and a trigger 150 for actuatingthe clamp member.

The carriage 142 comprises an upstanding part having a guide aperturethrough which the rod passes, with a small clearance, as it is fed tothe melt body. When a rod of adhesive is to be fed into the glue gunshown in FIG. 6, with the heater operating, an end portion of the rod isintroduced to the carriage 142 and through the inlet passage of theinlet tube 128, causing the sleeve to be distended to accommodate therod. Further pressure on the rod by operation of the trigger operatedfeeding means exerts a feed force on the rod and urges it to movethrough the lip means of the inlet tube, towards the melt body, and intothe inlet end 118 and into the inlet 117 of the melt chamber element. Aleading end portion of the rod engages the fin elements within the meltchamber, and the spring is compressed. As a result of transfer of heatfrom the melt body to the fin elements of the melt chamber and to theleading end portion of the rod, the rod is melted and subsequentportions of the rod are fed into the melt chamber. Continued exertion offeeding pressure on the rod causes the solid regions of the rod to notonly maintain compressive force of the melt chamber element on thespring but also exert pressure on the melted material in the meltchamber so to cause flow of melted material from the outlet 119 of themelt chamber element, through the portion of the passage containing thespring and out of the nozzle assembly. When the feeding pressure isremoved from the rod, forward pressure on the melt is relieved and flowof melted material from the nozzle assembly ceases. Also, the springexerts sufficient force on the melt chamber element to urge the rodoutwardly of the inlet end of the melt body and to move the rod a shortdistance outwardly through the inlet end and the inlet tube 128. In thisway pressure built up in the melt chamber is further relieved.

We claim:
 1. In a device for melting and dispensing thermoplasticmaterial supplied in the form of a rod, said device comprising means forapplication of a feeding force on the rod to urge it in a directiontowards a melt body and a melt body having an inlet adapted to receive arod of thermoplastic material, an outlet, a passage extending betweenthe inlet and outlet, and means for heating the melt body so thatmaterial which enters the passage via the inlet in the form of a rod maybe dispersed from the outlet in a molten condition;wherein theimprovement comprises resilient means located within the passage andarranged to exert sufficient force in a reverse direction to move therod outwardly of the melt body when the feeding force is not applied. 2.A device according to claim 1 wherein the resilient means comprises acoil spring.
 3. A device according to claim 2 wherein said coil springis in heat conductive contact with the melt body whereby it contributesto melting of the thermoplastic material.
 4. A device according to claim1 wherein said outlet comprises an orifice.
 5. A device according toclaim 1 wherein said resilient means is arranged to engage the solidportion of a rod fed into the melt chamber.
 6. A device according toclaim 2 wherein the device further comprises an inlet sleeve for guidinga rod to the inlet of the melt body, the sleeve having lip means forgripping engagement with the rod.
 7. A device according to claim 6wherein the diameter of the coil spring is larger than that of anopening described by the lip means.
 8. A device according to claim 1wherein a melt chamber is provided by a melt chamber element which ismovable with the passage in the melt body and the resilient means isarranged to engage the melt chamber element to move it in a directionoutwardly of the melt body when the feeding force is not applied.
 9. Adevice according to claim 8 wherein the passage in the melt body isprovided with a stop means whereby movement of the melt chamber elementtowards the inlet end is limited.
 10. A device according to claim 8wherein said outlet comprises a nozzle assembly.
 11. A device accordingto claim 10 wherein the resilient means is located within the passagebetween the outlet nozzle assembly and the melt chamber element.
 12. Ahot melt hand held glue gun which comprises a device according to claim1, 2, 5 or
 6. 13. A hot melt hand held glue gun which comprises a deviceaccording to claim 1, 8 or
 9. 14. A device according to claim 8 furthercomprising trigger operated means for feeding the rod into the meltchamber.
 15. A device according to claim 10 wherein said nozzle assemblyis releasably mounted and that the melt chamber element may be removedfrom the melt body when the nozzle assembly is released from the meltbody.
 16. A device according to claim 4 wherein said outlet comprises anozzle assembly.